“…However, it becomes higher than that at the 25 cm position after that indicating the importance of osmotic dilution and laticifer plugging in the latex flow and turgor pressure recovery 30 min after tapping. This result is consistent with dendrometric measurement of the rubber tree trunk diameter (Gooding 1952; Luštinec et al 1969) and bark contraction (Southorn 1967) at different distance below the tapping cut. It confirmed the newly developed PTPP could sensitively measure the quick change of the H. brasiliensis phloem turgor pressure which is an indication of the latex flow and phloem water relationship after tapping.Figure 7 Phloem turgor pressure variation at 5 cm and 25 cm beneath the tapping cut during latex flow.…”
Section: Resultssupporting
confidence: 88%
“…It could sensitively measure the rapid alteration of phloem turgor pressure for several hours (Figures 3, 4, 5, 6 and 7; Additional files 1, 2, 3, 4 and 5), and in accordance with tapping and daily transpiration induced trunk diameter (Gooding 1952; Luštinec et al 1969) and bark contraction (Southorn 1967). Therefore, the novel phloem turgor pressure probe is a reliable technique to accurately measure the real-time phloem turgor pressure.…”
Section: Discussionmentioning
confidence: 98%
“…Our field measurements showed that the measured turgor pressure values and tendencies are similar to that had been reported with capillary manometer methods (Buttery and Boatman 1964 , 1966 , 1967 ; Milburn and Ranasinghe 1996 ; Yeang 2005 ). It could sensitively measure the rapid alteration of phloem turgor pressure for several hours (Figures 3 , 4 , 5 , 6 and 7 ; Additional files 1 , 2 , 3 , 4 and 5 ), and in accordance with tapping and daily transpiration induced trunk diameter (Gooding 1952 ; Luštinec et al 1969 ) and bark contraction (Southorn 1967 ). Therefore, the novel phloem turgor pressure probe is a reliable technique to accurately measure the real-time phloem turgor pressure.…”
BackgroundAlthough the pressure flow theory is widely accepted for the transport of photoassimilates in phloem sieve elements, it still requires strong experimental validation. One reason for that is the lack of a precise method for measuring the real-time phloem turgor pressure from the sink tissues, especially in tree trunks.ResultsTaking the merits of Hevea brasiliensis, a novel phloem turgor pressure probe based on the state of the art cell pressure probe was developed. Our field measurements showed that the phloem turgor pressure probe can sensitively measure the real-time variation of phloem turgor pressure in H. brasiliensis but the calculation of phloem turgor pressure with xylem tension, xylem sap osmotic potential and phloem sap osmotic potential will under-estimate it. The measured phloem turgor pressure gradient in H. brasiliensis is contrary to the Münch theory. The phloem turgor pressure of H. brasiliensis varied from 8–12 bar as a consequence of water withdrawal from transpiration. Tapping could result in a sharp decrease of phloem turgor pressure followed by a recovery from 8–45 min after the tapping. The recovery of phloem turgor pressure after tapping and its change with xylem sap flow suggest the importance of phloem water relationship in the phloem turgor pressure regulation.ConclusionThe phloem turgor pressure probe is a reliable technique for measuring the real-time variation of phloem turgor pressures in H. brasiliensis. The technique could probably be extended to the accurate measurement of phloem turgor pressure in other woody plants which is essential to test the Münch theory and to investigate the phloem water relationship and turgor pressure regulation.Electronic supplementary materialThe online version of this article (doi:10.1186/1999-3110-55-19) contains supplementary material, which is available to authorized users.
“…However, it becomes higher than that at the 25 cm position after that indicating the importance of osmotic dilution and laticifer plugging in the latex flow and turgor pressure recovery 30 min after tapping. This result is consistent with dendrometric measurement of the rubber tree trunk diameter (Gooding 1952; Luštinec et al 1969) and bark contraction (Southorn 1967) at different distance below the tapping cut. It confirmed the newly developed PTPP could sensitively measure the quick change of the H. brasiliensis phloem turgor pressure which is an indication of the latex flow and phloem water relationship after tapping.Figure 7 Phloem turgor pressure variation at 5 cm and 25 cm beneath the tapping cut during latex flow.…”
Section: Resultssupporting
confidence: 88%
“…It could sensitively measure the rapid alteration of phloem turgor pressure for several hours (Figures 3, 4, 5, 6 and 7; Additional files 1, 2, 3, 4 and 5), and in accordance with tapping and daily transpiration induced trunk diameter (Gooding 1952; Luštinec et al 1969) and bark contraction (Southorn 1967). Therefore, the novel phloem turgor pressure probe is a reliable technique to accurately measure the real-time phloem turgor pressure.…”
Section: Discussionmentioning
confidence: 98%
“…Our field measurements showed that the measured turgor pressure values and tendencies are similar to that had been reported with capillary manometer methods (Buttery and Boatman 1964 , 1966 , 1967 ; Milburn and Ranasinghe 1996 ; Yeang 2005 ). It could sensitively measure the rapid alteration of phloem turgor pressure for several hours (Figures 3 , 4 , 5 , 6 and 7 ; Additional files 1 , 2 , 3 , 4 and 5 ), and in accordance with tapping and daily transpiration induced trunk diameter (Gooding 1952 ; Luštinec et al 1969 ) and bark contraction (Southorn 1967 ). Therefore, the novel phloem turgor pressure probe is a reliable technique to accurately measure the real-time phloem turgor pressure.…”
BackgroundAlthough the pressure flow theory is widely accepted for the transport of photoassimilates in phloem sieve elements, it still requires strong experimental validation. One reason for that is the lack of a precise method for measuring the real-time phloem turgor pressure from the sink tissues, especially in tree trunks.ResultsTaking the merits of Hevea brasiliensis, a novel phloem turgor pressure probe based on the state of the art cell pressure probe was developed. Our field measurements showed that the phloem turgor pressure probe can sensitively measure the real-time variation of phloem turgor pressure in H. brasiliensis but the calculation of phloem turgor pressure with xylem tension, xylem sap osmotic potential and phloem sap osmotic potential will under-estimate it. The measured phloem turgor pressure gradient in H. brasiliensis is contrary to the Münch theory. The phloem turgor pressure of H. brasiliensis varied from 8–12 bar as a consequence of water withdrawal from transpiration. Tapping could result in a sharp decrease of phloem turgor pressure followed by a recovery from 8–45 min after the tapping. The recovery of phloem turgor pressure after tapping and its change with xylem sap flow suggest the importance of phloem water relationship in the phloem turgor pressure regulation.ConclusionThe phloem turgor pressure probe is a reliable technique for measuring the real-time variation of phloem turgor pressures in H. brasiliensis. The technique could probably be extended to the accurate measurement of phloem turgor pressure in other woody plants which is essential to test the Münch theory and to investigate the phloem water relationship and turgor pressure regulation.Electronic supplementary materialThe online version of this article (doi:10.1186/1999-3110-55-19) contains supplementary material, which is available to authorized users.
The concentration of phloem solute generally falls from leaves to roots. However, a local increase in latex total solid content (LILTSC) was identified near the tapping cut of rubber trees. To understand the mechanism of ethephon-stimulated latex yield, the formation and ethephon (an ethylene releaser) alleviation of the LILTSC near the tapping cut were examined. It was found that the LILTSC near the tapping cut of a tapped rubber tree was caused by the tapping-accelerated rubber biosynthesis which began following the first tapping and became significant after the fourth tapping. Ethephon stimulation markedly reduced the LILTSC. The latex yield change pattern upon ethephon stimulation was associated with the kinetic change of LILTSC and the decomposition dynamic of ethephon into ethylene. Once the LILTSC was reduced by ethylene release upon ethephon stimulation, the latex yield increased; however, when the ethylene release upon ethephon stimulation receded, the LILTSC was restored and the effect of ethephon stimulation dissipated. The reduction of LILTSC by ethephon stimulation could be ascribed to the translocation property of ethylene in plants and its regulation of aquaporins. Because maximum ethylene release upon tapping-cut-ethephon-application occured close to the tapping cut, the aquaporins were more upregulated in this region, leading to a reduction of the LILTSC and an increase in latex yield. All these results suggest that the LILTSC near the tapping cut was caused by tapping; the ethephon-induced aquaporin up-regulation and LILTSC reduction are involved in the mechanism of ethephon-promoted latex yield.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
